Minimally-invasive, energy-based radiofrequency (RF) ablation is now in widespread clinical use to treat a wide range of small focal primary and metastatic tumors in the liver, kidney, and lung. Yet, we and others have recently confirmed initial clinical suspicions that local tumor ablation can have broad systemic pro-oncogenic effects, stimulating distant tumor growth and de novo oncogenesis. We have identified three key mediators (Interleukin-6, the HGF/c-Met complex, and VEGF) that are increased locally and/or systemically in concert with periablational recruitment of inflammatory cell populations, and have determined that these are key contributors to secondary systemic pro-oncogenic effects. Our preliminary studies also suggest that tumor receptor expression can identify those tumors that are most susceptible to such `off-target' tumorigenesis. Similarly, we demonstrate that well-selected use of adjuvant drugs to block key mediators can reduce early signs of oncogenic stimulation, though long-term survival studies are still required. Accordingly, we propose to systematically study these issues as a basis for developing a paradigm of combination therapy to block `off- target' pro-oncogenic effects in susceptible tumors with the intent of improving overall ablation outcome. In this proposal we will initially study the relative influence of three mediators (IL-6, HGF/c-Met, and VEGF) using selective gene silencing on the production of pro-oncogenic factors (Aim 1a). Next, we will study how selective mediator silencing affects three key cell populations (neutrophils, macrophages, and activated myofibroblasts) recruited to the ablation zone (Aim 1b), followed by selective depletion/inhibition of these cell populations to identify cellular contributions to key mediator production (Aim 1c). In Aim 2, we will overexpress or silence of IL-6, c-met, and VEGF tumor receptors to determine which distant tumors are most susceptible to `off-target' hepatic RFA effects and suppress stimulation of distant tumor growth for receptor positive or negative tumor lines using adjuvant receptor inhibitors. Finally, in Aim 3 we will perform long-term endpoint survival studies in pre-clinical models that simulate commonly encountered clinical situations, including hepatic ablation: 1) in the presence of a distant primary tumor in the liver and breast, 2) in cirrhotic liver pre-disposed to de novo hepati tumorigenesis, and 3) in the setting of diffuse progressive micrometastases. Thus, we will characterize key molecules and cell populations in a common mechanistic pathway that underlies hepatic RF ablation-induced pro-oncogenic effects, identify key tumor biomarkers that can be used to predict susceptibility to these effects and show response to adjuvant drug inhibition, and identify regimens that can be applied in three relevant pre-clinical / in situ tumo models that closely reproduce current clinical hepatic RF ablation applications. Thus, with the completion of this proposal we will be well-positioned to translate our paradigm into clinical studies in keeping with our track record of rapid translation of combination therapy regimens that have improved local image-guided tumor ablation efficacy.